Apparatus for forming glass sheets

ABSTRACT

An apparatus capable of accurately forming a heated glass sheet to a deep, abrupt, or complex curvature are disclosed as utilizing a first curved mold (42) that initially forms the glass sheet at a first forming station (20) preferably by the operation of gravity. The initially formed glass sheet is moved horizontally preferably by movement on the first curved mold (42) to a second forming station (22). A second curved mold (48) of the second forming station (22) engages the initially formed glass sheet to provide accurate forming preferably by downward movement of the second curved mold that provides the engagement thereof with the glass sheet. In the preferred construction disclosed, the heated glass sheet is transferred from a furnace conveyor (28) to a topside conveyor (32) for depositing onto the first curved mold (42), and a transfer conveyor (55) transfers the formed glass sheet from the second curved mold (48) to a quench station (24) for tempering.

TECHNICAL FIELD

This invention relates to a method and apparatus for forming glasssheets heated to a sufficiently high temperature to be deformable.

BACKGROUND ART

Many different types of systems and methods have previously been used todeform heated glass sheets from a flat shape to a curved shape. Forexample, vehicle windshields, side windows, and back windows areconventionally manufactured by heating flat glass sheets and thendeforming the glass sheets to the desired curvature for the particularvehicle windshield or window involved. Also, presently there is anincreasing use of curved architectural glass.

Different terminology has been utilized in the past to refer todeformation of flat glass sheets to a curved shape. The terms forming,bending, and shaping are all utilized to refer to such deformation ofglass sheets whether the finally curved shape is relatively shallow andeasy to perform, relatively deep or abrupt and harder to perform, orrelatively complex and hard to perform even if not particularly abruptor deep. Complex bends are glass shapes that have both concave andconvex curvatures on each surface of the glass sheet and may alsoinclude deep and/or abrupt bends. Such complex bends are becomingincreasingly difficult to manufacture with conventional forming methodsand systems.

U.S. Pat. Nos. 4,282,026, 4,437,871, and 4,437,872 of Harold A.McMaster, Norman C. Nitschke, and John S. Nitschke disclose a system forbending heated flat glass sheets relatively quickly to a curved shapeunder the force of gravity. This system includes a holder having adownwardly facing surface that receives a heated glass sheet from ahorizontal conveyor on which heating takes place. The holder thensupports the heated glass sheet above the conveyor in preparation forbending. A curved bending mold of the system is positioned under theholder and has at least a substantial portion with a greater curvaturethan the holder surface. The mold then receives the heated glass sheetfrom the holder for bending under the force of gravity. One preferredembodiment of the system utilizes a planar holder surface such that onlythe curved mold must be changed when different sizes and/or shapes ofglass sheets are to be bent. Another preferred embodiment disclosed formaking relatively deep bends includes a curved holder surface againstwhich the planar heated glass sheet received from the conveyor ispre-bent prior to gravity deformation below the curved holder on thecurved mold which has a greater curvature than that of the curved holdersurface.

U.S. Pat. No. 4,233,049 discloses another system for bending heated,flat glass sheets by releasing the glass sheets from a flat platen ontoa curved bending mold for bending.

U.S. Pat. No. 4,260,408 discloses a glass sheet forming system whereinan initial bending operation and a subsequent press forming operationbetween a pair of opposed molds both take place at the same station.

U.S. Pat. No. 4,356,018 of Harold A. McMaster discloses a method andapparatus for deep bending glass sheets by initially releasing oneportion thereof from a downwardly facing surface onto a curved bendingmold while retaining another portion of the glass sheet against thedownwardly facing surface by an upward flow of gas. Termination of theupward gas flow releases the other portion of the glass sheet in amanner that permits bending of the glass sheet to the curved shape ofthe mold without substantial sliding between the glass sheet and themold.

Vehicle windshields are conventionally made by supporting a pair ofglass sheets on a curved mold that is passed through an elongatedfurnace for slow sagging of the glass sheets to the mold shape.Thereafter, the curved glass sheets are laminated to each other by anintermediate layer of plastic in order to hold the glass in positionupon breakage.

Most glass sheet bending and forming is performed with open center ringtype molds or full surface molds. Open center ring type molds engageonly the periphery of the glass sheet being deformed and thus preventthe possibility of any marking of the center glass area and resultantloss in optical quality. Full surface molds engage the center as well asthe periphery of each glass sheet being deformed and thereby provide amore accurate control of the final shape of the center of the glasssheet.

DISCLOSURE OF INVENTION

An object of the present invention is to provide an improved method andimproved apparatus capable of accurately forming a heated glass sheeteven when relatively deep, abrupt, or complex curvature is involved.

In performing the method of the invention, a glass sheet is initiallyheated to a sufficiently high temperature to be deformable and is thenengaged while at a first position with a first curved mold to provideinitial forming of the glass sheet. The initially formed glass sheet ismoved horizontally to a second position and is then engaged at thesecond position with a second curved mold to further form the glasssheet. The initial forming at the first position and the subsequentforming at the second position provide accurate control of the finalshape even when relatively deep, abrupt, or complex curvature isinvolved.

In the preferred practice of the method, the heated glass sheet isreleased from a downwardly facing surface above the first curved mold toprovide the engagement that initially forms the glass sheet on the firstcurved mold by gravity. In one mode of operation, this downwardly facingsurface supports the glass sheet in a spaced relation thereto withoutany surface to surface engagement between the glass sheet and thedownwardly facing surface. In another mode of operation, the downwardlyfacing surface supports the glass sheet in an engaged relationship andis moved to transfer the glass sheet to the first curved mold. Theforming on the first mold is also disclosed as taking place as portionsof the first curved mold articulate with respect to each other in amanner that facilitates more difficult forming operations. Spot heatingof the glass sheet to assist the forming is also utilized to make theglass sheet softer and easier to form in areas where the curved shape isdifficult to form.

In the preferred practice of the method, the initially formed glasssheet is moved on the first curved mold from the first position to thesecond position for the further forming.

At the second position, the second curved mold is preferably engagedwith the initially formed glass sheet from above to provide the furtherforming of the glass sheet. Relative vertical movement between the firstand second curved molds is provided to engage the glass sheet with thesecond curved mold at the second position. In accordance with onepractice of the method, the second curved mold engaged with theinitially formed glass sheet has the same curvature as the first curvedmold such that the glass sheet can be pressed between the two curvedmolds to provide the further forming by the relative vertical movementbetween the curved molds. In another practice of the method, the secondcurved mold has a different curvature than the first curved mold and adifferential gas pressure is applied at the second curved mold toprovide the further forming to the shape thereof after the initialengagement therewith as provided by the relative vertical movementbetween the curved molds. In both modes of operation, the glass sheet isthereafter supported against a downwardly facing surface of the secondcurved mold by a differential gas pressure which may be provided by avacuum applied at the surface. An upward gas flow can also be used tosupply the differential gas pressure or assist the vacuum in supportingthe glass sheet against the second curved mold.

After the engagement of the second curved mold with the initially formedglass sheet to provide the further forming, relative vertical movementbetween the first and second curved molds takes place to disengage thefirst curved mold from the glass sheet which is then supported by thesecond curved mold. A transfer mold of a transfer conveyor is then movedunder the second curved mold and may be pressed against the secondcurved mold to form the glass sheet. The transfer mold is embodied by aring that receives the glass sheet from the second curved mold.Thereafter, the transfer ring is moved away from the second curved moldwith the glass sheet thereon for cooling of the glass sheet.

As disclosed, the formed glass sheet is rapidly cooled to providetempering of the glass sheet as conventionally done with vehicle sideand back windows. However, it is also possible to provide slower coolingof the formed glass sheet so as to be annealed in the manner utilizedwith vehicle windshields in the United States and many other countries.

In the preferred mode of operation, the relative vertical movementbetween the first and second curved molds is provided by moving thesecond curved mold vertically while the first curved mold remainsstationary. It is also possible to provide the vertical movement betweenthe first and second curved molds by moving the first curved moldvertically while the second curved mold either remains stationary or hasan accompanying vertical movement in the opposite direction. However,movement of the second curved mold vertically is preferred since thefirst curved mold is moved horizontally between the first and secondpositions and it is much easier to provide movement of each mold in onlyone direction as opposed to two different directions. In providing therelative vertical movement by movement of the second curved mold, bothdownward and upward movements of the second curved mold are involved.Downward movement of the second curved mold provides the initialengagement thereof with the initially formed glass sheet on the firstcurved mold in order to permit the forming on the second curved mold.Subsequent upward vertical movement of the second curved mold disengagesthe glass sheet supported thereby from the first curved mold inpreparation for the subsequent transferring previously described.

The improved apparatus of the invention is utilized to perform themethod thereof by forming a glass sheet heated to a sufficiently hightemperature to be deformable. This apparatus includes the first curvedmold previously described in connection with the method for engaging theheated glass sheet to provide initial forming of the glass sheet on thefirst curved mold. The apparatus also includes means for moving theinitially formed glass sheet horizontally to the second position fromthe first position where the first curved mold initially receives theglass sheet. The apparatus additionally includes the second curved moldthat engages the initially formed glass sheet at the second position tofurther form the glass sheet.

As previously discussed in connection with the description of themethod, the initial forming on the first curved mold and the subsequentforming on the second curved mold provides accurate control of the finalglass shape even when relatively deep, abrupt, or complex curvatures areinvolved.

In its preferred construction, the apparatus includes a topside conveyorhaving a topside platen with a downwardly facing surface for supportingthe heated glass sheet in a horizontally extending orientation and forreleasing the heated glass sheet onto the first curved mold for initialforming by gravity. This topside platen in one embodiment supports theheated glass sheet in a spaced relationship thereto without any surfaceto surface engagement between the glass sheet and its downwardly facingsurface. In another embodiment, the topside platen supports the heatedglass sheet in an engaged relationship and includes an actuator thatmoves the platen to transfer the glass sheet to the first curved mold. Afurnace having a roller conveyor for heating the glass sheet is alsoincorporated in the apparatus and supplies the heated glass sheet to thedownwardly facing surface of the topside platen at the first positionabove the first curved mold on which the initial forming takes place.

The first curved mold is also disclosed as having portions thatarticulate with respect to each other as the glass sheet is initiallyformed in order to perform more difficult forming operations. Spotheaters of the apparatus make the glass softer and easier to form inareas where the curved shape is difficult to form.

Preferably, the means of the apparatus for moving the glass sheethorizontally includes an actuator that moves the first curved moldbetween the first position where the glass sheet is received from thedownwardly facing surface of the topside platen and the second positionbelow the second curved mold. After the glass sheet is transferred fromthe first curved mold to the second curved mold, this actuator moves thefirst curved mold back to the first position in preparation for the nextcycle.

The preferred construction of the apparatus also includes anotheractuator for providing relative vertical movement between the first andsecond curved molds at the second position to provide the engagement ofthe second curved mold with the initially formed glass sheet. Thisactuator preferably moves the second curved mold downwardly to providethe engagement thereof with the initially formed glass sheet and,thereafter, moves the second curved mold upwardly with the glass sheetsupported thereon for movement out of engagement with the first curvedmold.

A transfer conveyor of the apparatus includes a transfer mold that maybe pressed against the second curved mold to form the glass sheet. Thetransfer mold is disclosed as being embodied by an open center transferring that receives the glass sheet from the second curved mold formovement away from the second curved mold. A further actuator providesthe transfer ring movement in a horizontal direction from below thesecond curved mold to an adjacent position.

As disclosed, the apparatus also includes a quench station for temperingthe formed glass sheet upon movement of the transfer ring by theactuator thereof from the second curved mold to between upper and lowerblastheads of the quench station.

A vacuum is drawn at the downwardly facing surface of the topside platenand pressurized gas is supplied thereto in accordance with the one modeof operation previously mentioned to provide support of each glass sheetin a spaced relationship below the topside platen in preparation forbeing released onto the first curved mold when the vacuum is terminated.Likewise, a vacuum is drawn at the topside platen in accordance with theother mode of operation previously mentioned to initially support theglass sheet in an engaged relationship. A vacuum is also drawn at adownwardly facing surface of the second curved mold to provide thesupport of each glass sheet on the second mold after disengagementthereof with the first curved mold as a result of the vertical movementtherebetween during the forming cycle. Both the initial and furtherforming preferably take place in a heated ambient. An upward gas flowsupplied by a number of gas jet pumps can also be utilized in the heatedambient if necessary to assist in supporting the glass sheet below thetopside platen and the second curved mold.

The objects, features, and advantages of the present invention arereadily apparent from the following detailed description of the bestmodes for carrying out the invention when taken in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side schematic view of a glass sheet forming systemincorporating apparatus that is constructed in accordance with theinvention and utilized to perform the glass sheet forming methodthereof;

FIG. 2 is a partial view of the glass sheet forming system andillustrates a furnace conveyor on which glass sheets are heated, atopside conveyor which has received a heated glass sheet from thefurnace conveyor, and a first curved mold illustrated at a firstposition adjacent the furnace conveyor;

FIG. 3 is a partial view of the forming system similar to FIG. 2 butwith the glass sheet released from the topside platen onto the firstcurved mold for initial forming of the glass sheet;

FIG. 4 is another partial view of the forming system and illustrates thefirst curved mold moved from its phantom line first position to thesolid line second position below a second curved mold that is utilizedto provide further forming of the initially formed glass sheet;

FIG. 5 is a view similar to FIG. 4 but illustrating another embodimentof the second curved mold which has a different curvature than the firstcurved mold unlike the embodiment of FIG. 4 wherein the two curved moldshave the same curvature;

FIG. 6 is a further partial view of the forming system illustrating thesecond curved mold, a transfer conveyor for receiving the glass sheetfrom the second curved mold, and a quench station for tempering theformed glass sheet;

FIG. 7 is a view similar to FIG. 6 but illustrating a transfer ring ofthe transfer conveyor moved to the quench station with the formed glasssheet thereon to provide the tempering;

FIG. 8 is a view similar to FIG. 1 of another system incorporatingapparatus constructed in accordance with the invention;

FIG. 9 is a view illustrating a second embodiment of the first moldwhich includes portions that are pivotally connected to each other andmovable during the initial glass sheet forming;

FIG. 10 is a view illustrating the second embodiment of the first moldafter movement of the portions thereof as the glass sheet forms to themold shape; and

FIG. 11 is a sectional view through a glass sheet which has been formedto a complex shape.

BEST MODES FOR CARRYING OUT THE INVENTION

With reference to FIG. 1 of the drawings, one embodiment of a glasssheet forming system constructed in accordance with the presentinvention is generally indicated by 10 and includes a furnace 12 of aninsulated construction that defines a heated chamber 14. Within theheated furnace chamber 14, apparatus 16 is located to provide glasssheet forming in accordance with the invention as is hereinafter morefully described. Both the apparatus 16 and the glass sheet formingmethod performed thereby constitute the invention and will be describedtogether to facilitate an appreciation of the complete invention.

As illustrated in FIG. 1, glass sheet forming system 10 includes aheating section 18, a first forming station 20, a second forming station22, and a quench station 24. The heating section 18, first formingstation 20, and second forming station 22 are all illustrated locatedwithin the heated chamber 14 of the furnace 12 while the quench station24 is located adjacent an access opening 26 through which formed glasssheets exit the furnace for rapid cooling at the quench station in orderto provide tempering of the formed glass sheets. Locating both the firstand second forming stations 20 and 22 within the heated chamber 14 ispreferable in order to avoid heat loss and thereby eliminate thenecessity of heating the glass sheets to a higher temperature so as toultimately be hot enough to permit the tempering at the quench station24.

With combined reference to FIGS. 1 and 2, the heating section 18 of thesystem includes a furnace conveyor 28 of the roller type including rolls30 on which glass sheets are heated within the furnace 12 duringconveyance at an elevation along a reference line A. A topside transferconveyor 32 includes a topside platen 34 having a downwardly facingsurface 36 of a flat shape located downstream from the roller conveyor28. The topside platen 34 receives a heated glass G sheet as the glasssheet is conveyed from the roller conveyor 28 as shown in FIG. 1 tobelow the platen surface 36 as shown in FIG. 2. The glass sheet G isreceived by the topside platen 34 and supported in a spaced relationshipjust below its surface 36 by a vacuum and pressurized gas supplied by apair of blowers 38 and 40 of the platen. Blower 38 draws a vacuum in afirst array of spaced holes in the platen surface 36, while the blower40 supplies pressurized gas to a second array of holes dispersed in theplaten surface 36 between the first array of holes. The vacuum allowsthe ambient gas pressure below the glass sheet to provide the supportthereof, while the pressurized gas spaces the glass sheet from theplaten surface 36 to prevent surface to surface engagement. The inertiaof the glass sheet as it is conveyed from the roller conveyor 28 andappropriate angling of the openings through which the pressurized gas issupplied provides conveyance of the glass sheet into engagement withsuitable locators for properly positioning the glass sheet in ahorizontally extending orientation in preparation for the formingoperation.

A first curved mold 42 of the forming station 20 has a curved portion 44and is positioned in a first position at the forming station 20 asillustrated in FIG. 3 to receive the glass sheet from the platen 34 forgravity forming. The curved mold 42 may be either of a peripheral ringtype having an open center or a continuous surface mold depending uponthe particular glass sheet being formed. As illustrated, the curvedportion 44 of mold 42 has a concave shape in an upwardly facingdirection such that peripheral portions of the glass sheet initiallyengage the mold and the center of the glass sheet thereafter deformsdownwardly under the impetus of gravity toward the shape of the mold toinitially form the glass sheet.

With combined reference to FIGS. 3 and 4, the first curved mold 42includes an actuator 46 that provides a preferred means for moving theinitially formed glass sheet from the first forming station 20 to asecond position at the second forming station 22 by horizontal movementof this mold which carries the glass sheet. During this horizontalmovement of the first curved mold 42, the force of gravity may continueto form the glass sheet in some cases while in others the glass sheetmay be fully formed to the shape of this mold prior to movement from thefirst forming station 20. For some shapes such as illustrated in FIG. 4,the glass sheet may not be able to bend fully to the shape of the firstcurved mold 42 solely under the influence of gravity.

Another embodiment of the first curved mold 42' is illustrated in FIG. 9and includes a main curved mold portion 44a as well as end curved moldportions 44b to which the main portion is pivotally connected in ahinged manner. The end mold portions are pivotally connected in a hingedmanner to the mold support frame. The heated glass sheet G has a flatshape upon initially being received by the mold 42'. The glass sheet Gforms to a curved shape as illustrated in FIG. 10 as the main moldportion 44a and end mold portions 44b articulate with respect to eachother about their pivotal connections under the force of gravity orother suitable actuation. Such mold articulation permits more difficultglass sheet forming to be performed than is otherwise possible. Also,spot heaters 45 may be utilized to provide localized heating thatsoftens the glass sheet in areas that are more difficult to form andthereby facilitates the forming operation.

It should be noted that while both of the first curved mold embodiments42 and 42' are illustrated as initially forming the glass sheet tocurvature in one direction, it is also possible for the initial formingto form the glass sheet to a complex curvature. Complex curvature ofglass sheets as illustrated in FIG. 11 involves forming the glass sheetso as to have both concave and convex curvatures on each of itssurfaces.

As illustrated in FIG. 4, the second forming station 22 includes asecond curved mold 48 that is positioned above the elevation of thefirst curved mold 42 after movement of the latter mold to the secondforming station in the manner previously described. The second curvedmold 48 has a downwardly facing surface 50 which has a differentcurvature than the initially formed shape of the glass sheet. Anactuator 52 provides relative vertical movement between the first andsecond curved molds 42 and 48 by moving the second curved mold 48vertically. Initially, the actuator 52 moves the second curved mold 48downwardly to the phantom line position illustrated to engage the curvedsurface 50 of the second curved mold with the initially formed glasssheet. As illustrated, the initially formed glass sheet is not fullyformed to the curved shape 44 of the first mold 42 which has the samecurvature as the curved surface 50 of the second mold 48. Continueddownward movement of the second curved mold 48 under the operation ofthe actuator 52 provides a pressing action which accurately forms theglass sheet to the shape of these two molds.

The second curved mold 48 also includes a blower or a gas jet pump 54,such as of the type disclosed by U.S. Pat. No. 4,222,763, for drawing avacuum through openings in the surface 50 to provide a differential gaspressure that secure the glass sheet to the second curved mold 48. Thisvacuum may also be applied to assist in the forming as the glass sheetis pressed between the molds. After the forming, upward movement of thesecond curved mold 48 lifts the glass sheet out of engagement with thefirst curved mold 42. The first curved mold 42 is then free to be movedhorizontally back to the bending station 20 by the actuator 46 inpreparation of the next cycle. The glass sheet remains supported on thedownwardly facing curved surface 50 of the second curved mold 48 inpreparation for subsequent transferring therefrom as is hereinafter morefully described.

As illustrated in FIG. 5, another embodiment of the second curved mold48 has a downwardly facing curved surface 50' which has a differentcurvature than the curved portion 44 of the first curved mold 42. In theparticular embodiment illustrated, the curved surface 50' has a centralformation 50'a of reverse curvature that defines a complex bend. Thevacuum applied at the downwardly facing surface 50' by the gas jet pump54 draws the glass sheet upwardly at the central formation 50'a to beformed to the complex shape of the second curved mold 48. Upwardmovement of the second curved mold 50' under the impetus of the actuator52 then moves the glass sheet out of engagement with the first curvedmold 42 which is then free to move back to the first forming station 20.As previously mentioned, the first curved mold 42 may also have acomplex shape and may also cooperate with a second curved mold ofcomplex shape like surface 50' to provide press forming in the mannerpreviously described in connection with FIG. 4. In such cases, thecomplex shape of the first mold 42 normally requires that the mold be ofthe full surface type as opposed to a peripheral ring type that onlyengages the periphery of the glass sheet.

The initial differential gas pressure support of the glass sheet againstthe curved surface 50 illustrated in FIG. 4 or the initial support andforming against the curved surface 50' illustrated in FIG. 5 may also beprovided by or assisted by upward gas flow from gas jet pumps located atthe forming station 22 below the elevation of the first curved mold 42.Such assistance requires that the first curved mold 42 have a ring shapefor engaging only the periphery of the glass sheet and an open center inorder to permit the upward gas flow toward the curved surface of thesecond curved mold. After the glass sheet is initially supported, thevacuum drawn by the gas jet pump 54 may be reduced in order to preventdeformation of the glass sheet at the openings through which the vacuumis drawn at the curved surface.

A transfer conveyor 55 of the apparatus is illustrated in FIG. 6 andincludes an open center mold embodied by a ring 56. An actuator 58 ofthe transfer conveyor 55 provides horizontal movement thereof to belowthe second curved mold 48 with the glass sheet supported on its lowercurved surface. The actuator 52 then moves the second curved mold 48downwardly into proximity with the transfer ring 56 to release the glasssheet by termination of the vacuum drawn by the gas jet pump 54. It isalso possible for the gas jet pump 54 to be reversed in order to supplypressurized gas to the mold surface 50 to force the glass sheetdownwardly away from the second curved mold 48 onto the transfer ring 56for movement away from the second curved mold. With some shapes, it mayalso be desirable to provide a pressing action between the second curvedmold 48 and the transfer ring 56 to insure that the glass sheet isaccurately formed prior to cooling to its final shape. A full surfacetransfer mold may also be used, as opposed to an open center ring, whenthe formed glass sheet is to be annealed instead of being tempered afterthe forming.

Actuator 58 of the transfer conveyor 55 is operated to move the ring 56and the formed glass sheet thereon from the second forming station 22 asillustrated in FIG. 6 to the quench station 24 illustrated in FIG. 7. Atthe quench station 24, upper and lower blastheads 60 and 62 provide gasflow that rapidly cools the opposite surfaces of the formed glass sheetto provide tempering. The open center of the transfer ring 56 isnecessary to permit the upward gas flow from the lower blasthead 62 toimpinge with the lower surface of the formed glass sheet.

Another system 10' constructed in accordance with the present inventionis illustrated in FIG. 8 and is similar to the previously describedsystem except as will be noted such that like reference numerals areapplied to like components thereof and much of the previous descriptionis applicable and need not be repeated. System 10' includes a topsidetransfer conveyor 32 having a platen 34 that is moved by an actuator 35between the solid and phantom line indicated positions illustrated toprovide transferring of heated glass sheets from the rolls 30 of theheating conveyor to the bending station 20. Platen 34 has a downwardlyfacing surface 36 of a flat shape located just above the conveyor rolls30. A vacuum is drawn at the surface 36, preferably by a gas jet pump 38of the same type as the gas jet pump 54 associated with the second mold48. A number of smaller gas jet pumps may also be utilized to provide anupward gas flow between the conveyor rolls 30 in order to assist thevacuum in lifting the glass sheet G from the conveyor up against theplaten surface 36 in an engaged relationship. Gas jet pump 38 may beoperated to decrease the extent of vacuum drawn after the initiallifting of the glass sheet upwardly from the conveyor such that there isno deformation of the heated glass sheet at openings in the surface 36through which the vacuum is drawn. Also, when the glass sheet isultimately released from the platen surface 36 for forming at theforming station 20, the vacuum drawn by the gas jet pump 38 isterminated and reverse operation thereof may also take place in order tosupply a positive pressure to the openings in the surface 36 so as tothereby force the glass sheet downwardly away from the platen.

After a glass sheet is received by the conveyor platen 34 in the solidline indicated position of FIG. 8, the actuator 35 moves the platen tothe phantom line indicated position whereupon the glass sheet isreleased in the manner described above onto the first curved mold 42 forthe forming operation as previously described. Actuator 35 than movesthe platen 34 back to the solid line indicated position in preparationfor the next cycle as the first curved mold 42 is moved from the firstforming station 20 to the second forming station 22.

It should also be noted, as previously mentioned, that in certainapplications the forming apparatus of the invention may also be utilizedto accurately form annealed glass such as is utilized in vehiclewindshields without a final tempering operation of the type specificallyherein described.

For a more complete understanding of the topside conveyor 32 illustratedin FIG. 1, reference should be made to the U.S. Patent Application Ser.No. 674,083 of Lee E. Fackelman for Glass Sheet Processing SystemIncluding Topside Transfer Apparatus which is being filed concurrentlyherewith and whose entire disclosure is hereby incorporated byreference.

For a more complete understanding of the topside conveyor 32 illustratedin FIG. 8, reference should be made to the U.S. Patent Application Ser.No. 590,770 filed on Mar. 19, 1984 in the name of Ronald A. McMaster forglass bending system including horizontally movable holder, the entiredisclosure of which is hereby incorporated by reference.

While the best modes for carrying out the invention have been describedin detail, other ways of practicing the invention are readily apparentas described by the following claims.

What is claimed is:
 1. Apparatus for forming a glass sheet heated to asufficiently high temperature to be deformable, the apparatuscomprising:a first curved mold for engaging the heated glas sheet at afirst position to provide initial forming of the glass sheet; anactuator for moving the first curved mold and the initially formed glasssheet thereon horizontally to a second position; and a second curvedmold for engaging the initially formed glass sheet from above at thesecond position to further form the glass sheet.
 2. Apparatus as inclaim 1 further comprising a topside platen having a downwardly facingsurface including means for drawing a vacuum to initially support theglass sheet and for subsequently terminating the vacuum to release theheated glass sheet onto the first curved mold for the initial forming bygravity.
 3. Apparatus as in claim 2 wherein the topside platen alsoincludes means for supplying positive pressure gas to the downwardlyfacing surface to support the heated glass sheet in a spacedrelationship thereto without any surface to surface engagement betweenthe glass sheet and the downwardly facing surface.
 4. Apparatus as inclaim 2 wherein the vacuum drawn at the downwardly facing surface of thetopside platen supports the heated glass sheet in an engagedrelationship therewith, and an actuator for moving the platen totransfer the glass sheet to the first curved mold.
 5. Apparatus as inclaim 1 wherein the first curved mold includes portions that articulatewith respect to each other as the glass sheet is initially formed. 6.Apparatus as in claim 5 further including at least one spot heater forheating the glass sheet to assist the forming on the curved mold havingthe portions that articulate with respect to each other.
 7. Apparatus asin claim 1 further including at least one spot heater for heating theglass sheet to assist the forming.
 8. Apparatus as in claim 1 furthercomprising a second actuator for providing relative vertical movementbetween the first and second curved molds at the second position toprovide engagement of the second curved mold with the initially formedglass sheet.
 9. Apparatus as in claim 8 wherein the second actuatormoves the second curved mold downwardly to provide the engagementthereof with the initially formed glass sheet, and the second actuatorthereafter moving the second curved mold upwardly with the glass sheetsupported thereon for movement out of engagement with the first curvedmold.
 10. Apparatus as in claim 9 further comprising a transfer conveyorfor receiving the glass sheet from the second mold for movement awayfrom the second curved mold.
 11. Apparatus as in claim 10 wherein thetransfer conveyor includes an open center transfer ring that receivesthe glass sheet, and an actuator for providing horizontal movement ofthe transfer ring from below the second curved mold to an adjacentposition.
 12. Apparatus as in claim 10 wherein the transfer conveyorincludes a mold for pressing the glass sheet against the second curvedmold to provide forming of the glass sheet.
 13. Apparatus as in any oneof claims 1 through 12 further comprising a quench station for temperingthe formed glass sheet.
 14. Apparatus for forming a glass sheet heatedto a sufficiently high temperature to be deformable, the apparatuscomprising:a topside platen having a downwardly facing surface andincluding means for drawing a vacuum to initially support a heated glasssheet in a horizontally extending orientation at a first position; afirst curved mold for receiving the heated glass sheet from thedownwardly facing platen surface upon termination of the vacuum toinitially gravity form the glass sheet on the first curved mold; anactuator for moving the first curved mold with the initially formedglass sheet thereon horizontally to a second position; and a secondcurved mold for engaging the initially formed glass sheet from above atthe second position to further form the glass sheet.
 15. Apparatus forforming a glass sheet heated to a sufficiently high temperature to bedeformable, the apparatus comprising:a furnace including a rollerconveyor on which a glass sheet is conveyed for heating; a topsideconveyor for receiving the heated glass sheet from the furnace rollerconveyor, said topside conveyor including a platen having a downwardlyfacing surface and including means for drawing a vacuum to initiallysupport the heated glass sheet in a horizontally extending orientationat a first position; a first curved mold for receiving the heated glasssheet from the downwardly facing platen surface upon termination of thevacuum to provide initial gravity forming of the glass sheet on thefirst curved mold; an actuator for moving the first curved mold with theinitially formed glass sheet thereon horizontally to a second position;a second curved mold positioned above the initially formed glass sheetat the second position and having a different shape than the initiallyformed shape of the glass sheet; an actuator for moving the secondcurved mold downwardly into engagement with the initially formed glasssheet to provide further forming of the glass sheet, the actuator of thesecond curved mold thereafter moving the second curved mold upwardlywith the glass sheet supported thereby for movement out of engagementwith the first curved mold; and a transfer conveyor for receiving theglass sheet from the second curved mold for movement away from thesecond curved mold.
 16. Apparatus for forming a glass sheet heated to asufficiently high temperature to be deformable, the apparatuscomprising:a furnace including a roller conveyor on which a glass sheetis conveyed for heating; a topside conveyor for receiving the heatedglass sheet from the furnace roller conveyor, said topside conveyorincluding a platen having a downwardly facing surface and includingmeans for drawing a vacuum to initially support the heated glass sheetin a horizontally extending orientation at a first position; a firstcurved mold for receiving the heated glass sheet from the downwardlyfacing platen surface upon termination of the vacuum to provide initialgravity forming of the glass sheet on the first curved mold; an actuatorfor moving the first curved mold with the initially formed glass sheetthereon horizontally to a second position; a second curved mold positionabove the initially formed glass sheet at the second position and havinga different shape than the initially formed shape of the glass sheet; anactuator for moving the second curved mold downwardly into engagementwith the initially formed glass sheet to provide further forming of theglass sheet, the actuator of the second curved mold thereafter movingthe second curved mold upwardly with the glass sheet supported therebyfor movement out of engagement with the first curved mold; an opencenter transfer ring for receiving the glass sheet from the secondcurved mold; an actuator for moving the transfer ring with the glasssheet thereon horizontally from below the second curved mold; and aquench station to which the transfer ring actuator moves the transferring for rapid cooling that tempers the formed glass sheet.